initial commit of janssonxx.h

janssonxx.h

@@ -0,0 +1,207 @@
+#if !defined(JANSSONXX_H)
+#define JANSSONXX_H 1
+
+#include <string>
+#include <jansson.h>
+
+namespace jansson {
+
+class Iterator;
+
+// represents any JSON value
+class Value {
+public:
+	// construct new Value with an undefined value
+	Value() : _value(0) {}
+
+	// free Value resources
+	~Value() { json_decref(_value); }
+
+	// copy an existing Value
+	Value(const Value& e) : _value(json_incref(e._value)) {}
+
+	// make a reference to an existing json_t value
+	explicit Value(json_t* value) : _value(json_incref(value)) {}
+
+	// copy an existing Value
+	Value& operator=(const Value& e) {
+		json_decref(_value);
+		_value = json_incref(e._value);
+		return *this;
+	}
+
+	// take ownership of a json_t (does not increase reference count)
+	Value& take_ownership(json_t* value) {
+		json_decref(_value);
+		_value = value;
+		return *this;
+	}
+
+	// load a file as a JSON value
+	static Value load_file(const char* path, json_error_t* error = 0) {
+		return Value().take_ownership(json_load_file(path, error));
+	}
+
+	// load a string as a JSON value
+	static Value load_string(const char* string, json_error_t* error = 0) {
+		return Value().take_ownership(json_loads(string, error));
+	}
+
+	// get the underlying json_t
+	json_t* as_json_t() const { return _value; }
+
+	// check Value value type
+	bool is_undefined() const { return _value == 0; }
+	bool is_object() const { return json_is_object(_value); }
+	bool is_array() const { return json_is_array(_value); }
+	bool is_string() const { return json_is_string(_value); }
+	bool is_integer() const { return json_is_integer(_value); }
+	bool is_real() const { return json_is_real(_value); }
+	bool is_number() const { return json_is_number(_value); }
+	bool is_true() const { return json_is_true(_value); }
+	bool is_false() const { return json_is_false(_value); }
+	bool is_boolean() const { return json_is_boolean(_value); }
+	bool is_null() const { return json_is_null(_value); }
+
+	// get size of array or object
+	unsigned int size() const {
+		if (is_object())
+			return json_object_size(_value);
+		else if (is_array())
+			return json_array_size(_value);
+		else
+			return 0;
+	}
+
+	// get value at array index
+	const Value at(unsigned int index) const {
+		if (is_array())
+			return Value(json_array_get(_value, index));
+		else
+			return Value();
+	}
+
+	const Value operator[](signed int index) const { return at(index); }
+	const Value operator[](unsigned int index) const { return at(index); }
+	const Value operator[](signed short index) const { return at(index); }
+	const Value operator[](unsigned short index) const { return at(index); }
+	const Value operator[](signed long index) const { return at(index); }
+	const Value operator[](unsigned long index) const { return at(index); }
+
+	// get object property
+	const Value get(const char* key) const {
+		if (is_object())
+			return Value(json_object_get(_value, key));
+		else
+			return Value();
+	}
+
+	const Value get(const std::string& key) const { return get(key.c_str()); }
+	const Value operator[](const char* key) const { return get(key); }
+	const Value operator[](const std::string& key) const { return get(key.c_str()); }
+
+	// clear all array/object values
+	void clear() {
+		if (is_object())
+			json_object_clear(_value);
+		else if (is_array())
+			json_array_clear(_value);
+	}
+
+	// get value cast to specified type
+	const char* as_cstring() const { return json_string_value(_value); }
+	std::string as_string() const { return as_cstring(); }
+	int as_integer() const { return json_integer_value(_value); }
+	double as_real() const { return json_real_value(_value); }
+	double as_number() const { return json_number_value(_value); }
+	bool as_boolean() const { return is_true(); }
+
+	// assign new string value
+	Value& operator=(const char* value) {
+		json_decref(_value);
+		_value = json_string(value);
+		return *this;
+	}
+
+	// assign new integer value
+	Value& operator=(int value) {
+		json_decref(_value);
+		_value = json_integer(value);
+		return *this;
+	}
+
+	// assign new real/double/number value
+	Value& operator=(double value) {
+		json_decref(_value);
+		_value = json_real(value);
+		return *this;
+	}
+
+	// assign new boolean value
+	Value& operator=(bool value) {
+		json_decref(_value);
+		_value = value ? json_true() : json_false();
+		return *this;
+	}
+
+private:
+	// internal value pointer
+	json_t* _value;
+};
+
+// iterators over a JSON object
+class Iterator {
+public:
+	// construct a new iterator for a given object
+	Iterator(const Value& value) : _object(value), _iter(0) {
+		_iter = json_object_iter(_object.as_json_t());
+	}
+
+	// increment iterator
+	void next() {
+		if (_iter != 0)
+			_iter = json_object_iter_next(_object.as_json_t(), _iter);
+	}
+
+	Iterator& operator++() { next(); return *this; }
+
+	// test if iterator is still valid
+	bool valid() const { return _iter != 0; }
+	operator bool() const { return valid(); }
+
+	// get key
+	const char* ckey() const {
+		if (_iter != 0)
+			return json_object_iter_key(_iter);
+		else
+			return "";
+	}
+
+	std::string key() const { return ckey(); }
+
+	// get value
+	const Value value() const {
+		if (_iter != 0)
+			return Value(json_object_iter_value(_iter));
+		else
+			return Value();
+	}
+
+	// dereference value
+	const Value operator*() const { return value(); }
+
+private:
+	// disallow copying
+	Iterator(const Iterator&);
+	Iterator& operator=(const Iterator&);
+
+	// object being iterated over
+	Value _object;
+
+	// iterator value
+	void* _iter;
+};
+
+} // namespace jansson
+
+#endif